A battery management system generally is divided into a centralized battery management system and a distributed battery management system. The distributed battery management system generally comprises a battery management control module and at least one data acquisition module, in which the data acquisition module is used for collecting parameters such as voltages, electric currents or temperatures of a plurality of battery cells. One advantage of the distributed battery management system is being capable of managing the battery cells and making equalization charging easy. With the increase in the number of the battery cells, the port resources of the battery management control module may be easy to expand, and the problem of wire harnessing may be easy to solve. However, the number of the data acquisition modules may increase with the number of the battery cells. The distributed battery management system uses a plurality of data acquisition modules, and in order to reduce costs, the data acquisition modules used by the distributed battery management system are the same, which may bring the CAN (Controller Area Network) reread problem among the data acquisition modules.
For the communication between a plurality of data acquisition modules and the battery management control module, solving the problem of data communication conflict has become the first and foremost task. At present, there are four main methods to solve the problem of the communication conflict of the distributed management system.
The first method is to assign different CAN bus identities (ID) for each data acquisition module, and to use a different application program on each module. This method makes the management of the application programs difficult, and consequently it becomes difficult for the data acquisition modules to be mounted in a vehicle, and the post-maintenance becomes difficult as well.
The second method is to add an identification module to the hardware of each data acquisition module. Different data acquisition modules have different identification modules to be identified with a program to solve the problem of communication conflict. This method causes difficulty during the producing and managing of the data acquisition module, and consequently it becomes difficult for the data acquisition modules to be mounted in a vehicle, and the post-maintenance becomes difficult as well.
The third method is to couple an external jumper circuit to the data acquisition module, to make use of the jumper circuit to set different statuses for the I/O port of each data acquisition module, and to give a CAN bus address corresponding to each data acquisition module for each status of the I/O port, so as to distinguish signals from each data acquisition module and to solve the problem of communication conflict of the distributed battery management system. Compared with the first and the second methods, one advantage of this method is that different application programs for each module is not needed, the hardware modules are uniform, and the battery cells are easy to manage. However, the external jumper needs to be set manually and is error-prone. Once an error is introduced, the method cannot self-identify and self-correct the error.
The fourth method is to couple a plurality of data acquisition modules in series, and to couple the battery management control module with the first data acquisition module in the series. After the first data acquisition module is activated, the next data acquisition module connected in series is activated, to distribute the identification among the modules. One advantage of this method is that it realizes the identification distribution by software, and the design is simple. However, because different data acquisition modules in the series have different functions, the application programs on the modules may also be different. This brings inconvenience to the design of the data acquisition modules and limits the selection of the data acquisition module, since a corresponding data acquisition module needs to be selected based on the sequence of activation. Moreover, because the data acquisition modules coupled in series are activated sequentially, if a line connecting two data acquisition modules is broken, the identification distribution will fail, and the entire system will be paralyzed.
Thus, there is a need for a distributed battery management system which allows convenient assignment of identification of individual data acquisition modules, and is easily scalable.